title: Effects of exercise on VLDL-triglyceride oxidation and turnover.
abstract: Lipids are important substrates for oxidation at rest and during exercise. Aerobic exercise mediates a delayed onset decrease in total and VLDL-triglyceride (TG) plasma concentration. However, the acute effects of exercise on VLDL-TG oxidation and turnover remain unclear. Here, we studied the acute effects of 90 min of moderate-intensity exercise in healthy women and men. VLDL-TG kinetics were assessed using a primed constant infusion of ex vivo labeled [1-(14)C]triolein VLDL-TG. Fractional VLDL-TG-derived fatty acid oxidation was measured from (14)CO(2) specific activity in expired air. VLDL-TG concentration was unaltered during exercise and early recovery, whereas non-VLDL-TG concentration decreased significantly.VLDL-TG secretion rate decreased significantly during exercise and remained suppressed during recovery. Total VLDL-TG oxidation rate was unaffected by exercise. However, the contribution of VLDL-TG oxidation to total energy expenditure fell from 14 ± 9% at rest to 3 ± 4% during exercise. We conclude that VLDL-TG fatty acids are quantitatively important oxidative substrates under basal postabsorptive conditions but remain unaffected during 90-min moderate-intensity exercise and, thus, become relatively less important during exercise. Lower VLDL secretion rate during exercise may contribute to the decrease in TG concentrations during and after exercise.
authors.affiliation: Dept. of Endocrinology and Internal Medicine, Aarhus Univ. Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark.
authors.forename: Esben
authors.initials: E
authors.lastname: Sondergaard
authors.forename: Iben
authors.initials: I
authors.lastname: Rahbek
authors.forename: Lars P
authors.initials: LP
authors.lastname: Sørensen
authors.forename: Jens S
authors.initials: JS
authors.lastname: Christiansen
authors.forename: Lars C
authors.initials: LC
authors.lastname: Gormsen
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology; D002153:Calorimetry, Indirect; D002245:Carbon Dioxide / Q000378:metabolism; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D010168:Palmitates / Q000378:metabolism; D012727:Sex Characteristics; D014280:Triglycerides / Q000378:metabolism*; D055815:Young Adult
chemical_list: D005227:Fatty Acids; D008079:Lipoproteins, VLDL; D010168:Palmitates; D014280:Triglycerides; C030106:very low density lipoprotein triglyceride; D002245:Carbon Dioxide